Welcome to the forum.
I think you are asking about the difference between "foreign" and "foreigner"? If so, you should check a dictionary first.
'Foreign' is an 'adjective'; foreigner is a 'noun'. That should give you a clue.
For some reason, Spanish people have difficulty with the idea that a foreigner is a foreign person. In the same way, you can't have '[STRIKE]a Spanish[/STRIKE]' (un español). ;-)